The attr channels indicates the desired number of color channels for the
decoded image.

Accepted values are:

0: Use the number of channels in the JPEG-encoded image.

1: output a grayscale image.

3: output an RGB image.

If needed, the JPEG-encoded image is transformed to match the requested number
of color channels.

The attr ratio allows downscaling the image by an integer factor during
decoding. Allowed values are: 1, 2, 4, and 8. This is much faster than
downscaling the image later.

This op also supports decoding PNGs and non-animated GIFs since the interface is
the same, though it is cleaner to use tf.image.decode_image.

Args:

contents: A Tensor of type string. 0-D. The JPEG-encoded image.

channels: An optional int. Defaults to 0.
Number of color channels for the decoded image.

ratio: An optional int. Defaults to 1. Downscaling ratio.

fancy_upscaling: An optional bool. Defaults to True.
If true use a slower but nicer upscaling of the
chroma planes (yuv420/422 only).

try_recover_truncated: An optional bool. Defaults to False.
If true try to recover an image from truncated input.

acceptable_fraction: An optional float. Defaults to 1.
The minimum required fraction of lines before a truncated
input is accepted.

dct_method: An optional string. Defaults to "".
string specifying a hint about the algorithm used for
decompression. Defaults to "" which maps to a system-specific
default. Currently valid values are ["INTEGER_FAST",
"INTEGER_ACCURATE"]. The hint may be ignored (e.g., the internal
jpeg library changes to a version that does not have that specific
option.)